Accurate, reliable and easy to use TDS, EC &Temp water tester reader, with backlit and auto-lock function.No-this is not the cheapest meter...and there are reasons why! Not an outdated model being dumped on the market. Comes with the most comprehensive, easy-to-read TDS water quality guide that explains how to use the meter and what the results mean. With 30-years in the water purification business, we know water! ✔MULTIPURPOSE TDS TESTER: Test the purity of drinking water to ensure it's healthy, monitor if Reverse Osmosis (RO)/DI System Zero Water works properly, whether filter need replaced, aquarium maintenance, hydroponics EC (test nutrients), pool and spa, etc. ✔EASY AND INSTANTLY: Just turn TDS meter on and stir water gently, then stabilized readings will be auto-locked on LCD in seconds, and the tds ppm meter will shut off automatically if without operation over 2 minutes. ✔MULTIFUNCTIONAL AND UPGRADED: Professional TDS (Total Dissolved Solids), EC (Electrical Conductivity) and Temperature Meter 3 in 1. Upgraded with big backlit LCD for easier reading, and auto-lock function for easier use. TWhy this model is better: Custom-manufactured with premium electronics of our specification. Advanced digital ppm meter pen with Advanced Microprocessor Technology, combines TDS Meter(Total Dissolved Solids), EC Meter(Electrical Conductivity) and Temperature meter all in one easy to use pen.Uses premium quality titanium alloy probes, and an efficient intelligent chip that ensures stable performance but also contributes to exceptional accuracy, making it a trustworthy water quality tester. Upgraded water-proofing of the probe electronics compartment. Cheap TDS meters leak and short out!Test your distilled water, water machine water, bottled water.Test EC for hydroponics. Meter reads in microsiemens.Pool salt meters are really TDS meters! We include the simple conversion factor that lets you estimate pool salt levels. Features: Automatic Temperature Compensation (ATC)Equipped with backlit LCD for easy reading. Auto-Lock Function: From test beginning, the reading can be stabilized in seconds, and locked automatically for easy read and record.Hold Function: Before reading locked automatically, the reading can be locked manually if press “HOLD”.For water hardness testing we recommend out Water Hardness Test Strips-See our other items.